A thermostatic expansion valve is used on many types of air conditioning and refrigeration systems, and controls refrigerant flow through the system to match compressor capacity. Thermostatic expansion valves typically include a power element comprising a diaphragm mounted between a domed head and a support cup on the valve body. A fluid “charge” is located within a head chamber defined by the domed head and one (upper) surface of the diaphragm. The support cup and the other (lower) surface of the diaphragm define a diaphragm chamber with the body of the expansion valve. A valve stem extends downwardly from the diaphragm through a bore in the valve body to a valve element modulating a valve orifice between i) an inlet fitting directing liquid refrigerant (from the condenser) at high pressure into the valve body, and ii) an outlet fitting directing the refrigerant from the valve body at low pressure to the evaporator. Proctor, U.S. Pat. No. 3,667,247; Treder, U.S. Pat. No. 3,537,645; and Orth, U.S. Pat. No. 4,542,852, for example, show such expansion valves.
To control the refrigerant flow, the diaphragm in the power element moves in response to the refrigerant condition exiting the evaporator and compensates the flow rate to the evaporator by opening or closing the valve orifice. One type of device used to communicate the refrigerant condition to the diaphragm is a feeler bulb. The feeler bulb is positioned in contact with a pipe carrying the refrigerant, and a tube extends from the feeler bulb to the diaphragm chamber such that the charge in the diaphragm chamber is at essentially the temperature of the refrigerant at the location of the bulb. Refrigerant pressure against the bottom of the diaphragm along with the force of an adjustment spring on the valve element tends to close the valve, while pressure from the charge tends to open the valve. A feeler bulb is of course only one example of a known device that senses the refrigerant condition and communicates the condition to the power element. Other devices and techniques are of course known to those in the industry.
In certain applications, it is desirable to support the expansion valve in relatively close proximity to the condenser/heat exchanger. The valve should be supported in a manner that is rigid enough to prevent damage or refrigerant leakage from the valve due to movement, vibration, etc. of the support location. Ease of installation and removal of the valve such as for inspection and repair, at the both the manufacturing and field locations, is also often desirable. It is known to use a bracket to support the refrigeration valve directly against the side panel of a cabinet or enclosure. In one application, a U-shaped notch is provided along the side of a bracket plate, and the plate is slid laterally onto the inlet fitting of the valve. The fitting includes a fixed nut, and the bracket is slid up against the inner side surface of the nut and fastened thereto such as with one or more rivets or by brazing. The fitting is then inserted through an opening in the cabinet, with the bracket located adjacent the outer surface of the cabinet. Bolts are received through apertures in the plate and corresponding apertures in the cabinet, and nuts are tightened down on the bolts to rigidly attach the valve to the cabinet.
After assembly of the valve on the cabinet, the valve is fluidly connected to the refrigeration system. The refrigerant line from the condenser, with its own fitting, is screwed on the inlet fitting. A backup wrench is used to hold the nut on the inlet fitting while the fitting of the refrigerant line is tightened. Care must be taken to prevent over-torquing of the inlet fitting, as the braze/rivet connection of the bracket to the inlet fitting can fail, which would disconnect the valve from the cabinet and render it unusable. Sliding a backup wrench around the hex nut on the inlet fitting can be difficult and awkward depending on the location of the valve and the space available in the cabinet. And, of course, this also requires keeping such a backup wrench handy for the installation and removal of the refrigerant valve.
It is therefore believed there is a demand in the industry for an improved refrigeration valve, and particularly for a refrigeration valve having an improved attachment technique to attach the valve to a cabinet or other support surface, which overcomes many of the above-described drawbacks, and which is robust, simple, and rapid.